A Study Of New STR Loci And Validation Of Multiplex PCR In Forensic Science

Objective. The purpose of our work is to find new STR loci for forensic medicine and develop a set of fluorescent multiplex STR system for forensic DNA typing as well as to validate the forensic application of the system under the guidelines of TMGDAM (The Technology Working Group on DNA Analysis Methods) in order to address concerns presented in today's legal environment. Methods. A study of the allele structure and genetic polymorphism at five STR loci in Chinese Han population was carried out. A set of primers were designed to carry out a multiplex PCR for three STR loci D20S601, D6S474 and D6S2418. Using our primer set, three STR loci were amplified and the products of the multiplex PCR were genotyped by ABI PRISM(?) 310 Genetic Analyzer. The multiplex STR system was evaluated under variety conditions. Validation study of Forensic Science includedconcordance studies, sensitivity, reproducibility and performance of typing forensic samples. Result. The allele structure and genetic polymorphism at five STR loci were obtained. A fluorescent multiplex STR system, including D20S601, D6S474 and D6S2418 was developed. The reaction conditions of multiplex PCR were shown to be optimal yet robust enough to withstand moderate variations. Genotyping with 0.25 ng DNA was successful. Environmental and matrix source analyses revealed an ability of our fluorescent multiplex STR system to obtain complete genotypes in all samples except those exposed to 60℃ for 20-50 days. Conclusion. The multiplex PCR is an efficient method to amplify STR loci. It is achieved easily and reproducibly by simple adjustment of the individual primer concentrations. Our fluorescent multiplex STR system can be analyzed by capillary electrophoresis with laser detecting system and provide a new sources of typing regent for this technique platform. The validation study showed that our fluorescent multiplex STR system satisfied the TMGDAM guideline and it can be used for forensic casework.